Nicky Reilly suffered facial injuries in Thursday's blast
Police are continuing to question two men detained in an operation linked to an explosion in a restaurant in Exeter.
Armed officers targeted the men at a cafe in Plymouth city centre on Friday afternoon. One man was arrested and the other is said to be helping police.
The operation was linked to Thursday's explosion in Exeter, over which Nicky Reilly, 22, has been arrested.
Meanwhile, sources close to the investigation revealed police were aware of Mr Reilly prior to his arrest.
Police arrested Mr Reilly, from Plymouth, on Thursday after an explosive device detonated inside the Giraffe restaurant in Exeter.
It is thought there were two further devices which were recovered from the scene and made safe.
Police said Mr Reilly boarded a number X38 double-decker Stagecoach bus in Bretonside bus station, Plymouth, on Thursday morning and have appealed to passengers on the service to contact them.
He was taken to hospital following the explosion where he remains under police guard in a stable condition.
"He has not been formally interviewed," said a police spokesman.
Officers later revealed Mr Reilly had a history of mental illness and Deputy Chief Constable Tony Melville said on Thursday evening that police believed he had adopted the Islamic faith and had been "preyed upon" and "radicalised".
A bomb disposal team arrived at Mr Reilly's home in the Stonehouse area of Plymouth at lunchtime on Friday and police investigations are continuing at the flat.
In Friday's operation, armed police targeted two men who were drinking at the Bagatelle cafe in Plymouth.